Troubleshooting
Problem
When using SVC 5.1.0.0 - 5.1.0.3, the data rates published for FlashCopy background copy and cleaning rate are incorrect for maps which use a non-default (64KB) grain size.
Cause
The following table provides the relationship of the FlashCopy background copy and cleaning rates to the user specified rate when using SVC 5.1.0.0 - 5.1.0.3:
User specified value | Data copied/sec with 256 KB grain size | Data copied/sec with 64KB grain size |
1-10 | 128 KB | 32 KB |
11-20 | 256 KB | 64 KB |
21-30 | 512 KB | 128 KB |
31-40 | 1 MB | 256 KB |
41-50 | 2 MB | 512 KB |
51-60 | 4 MB | 1 MB |
61-70 | 8 MB | 2 MB |
71-80 | 16 MB | 4 MB |
81-90 | 32 MB | 8 MB |
91-100 | 64 MB | 16 MB |
These values represent the rates which an SVC cluster tries to achieve in an optimal environment, where there are no performance constraints.
Resolving The Problem
This issue was resolved in the 5.1.0.4 release of the SAN Volume Controller software, where a given user specified rate achieves the same data rate independent of the grain size used for the mapping.
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Document Information
Modified date:
17 June 2018
UID
ssg1S1003620